GU5.3 12v or 240v - how to identfy

[stillp]

This might be interesting: https://webstore.iec.ch/preview/info_iec60061-1{ed3.35}b.img.pdf

I don't have a copy of the full standard.

 

[JohnW2]

This might be interesting: https://webstore.iec.ch/preview/info_iec60061-1{ed3.35}b.img.pdf I don't have a copy of the full standard.

Thanks. As you say, it might well be interesting - but if we can't get access to the full standard, we may have to remain 'none the wiser'.

Kind Regards, John

 

[stillp]

I posted that link so you can get an idea of the content of the standard. However, it seems that I can access it, but only piecemeal. Watch this space while I try to find a way round that...

 

[JohnW2]

I posted that link so you can get an idea of the content of the standard.

I realise that, and I agreed that it could well be interesting because many of the 'sheets' referred to in that list of Contents appear to relate directly to issues we have been discussing. However, in a sense that is rather 'cruel', because it tells us that the answers might be there without allowing us to see them

However, it seems that I can access it, but only piecemeal. Watch this space while I try to find a way round that...

That sounds more like it. Thanks!

Kind Regards, John

 

[stillp]

OK, I now have access!
Not sure how useful that will be though. The designation letter 'G' means only that the lamp cap has "two or more projecting contacts, such as pins or posts", but 'U' is not in the list of defined second letters. It then goes on to state that "A lamp cap characterized in accordance with the rules in this specification may receive a designation already reserved for an existing cap. If such caps are not (or not perfectly) interchangeable with due regard to electrical or mechanical requirements, a capital X, Y, Z or U, or a combination of two or more of these, is added to the primary designation of the cap. These modifying letters follow the primary designation."
So it seem that G5.3 and GU5.3 are not fully interchangeable.

 

[JohnW2]

Not sure how useful that will be though. The designation letter 'G' means only that the lamp cap has "two or more projecting contacts, such as pins or posts", but 'U' is not in the list of defined second letters. ...

Thanks, and interesting. Do X, Y or Z appear in the list of defined second letters?

It then goes on to state that "A lamp cap characterized in accordance with the rules in this specification may receive a designation already reserved for an existing cap. If such caps are not (or not perfectly) interchangeable with due regard to electrical or mechanical requirements, a capital X, Y, Z or U, or a combination of two or more of these, is added to the primary designation of the cap. These modifying letters follow the primary designation." ... So it seem that G5.3 and GU5.3 are not fully interchangeable.

It sounds a bit like that, but presumably the "lack of perfect interchangeability" does not have to be two-way. In other words, if what I read previously is correct (that "U" indicates provision for mechanical restraint), it would not necessarily follow that a G5.3 could not be used in a GU3.55.3 holder (merely that the retaining clip/whatever would then be redundant.

Having said that, as I commented before, although G4 seems quite common, I'm not sure that I have seen a lamp/bulb described as G5.3 (they all seem to be GU5.3).

Kind Regards, John
Edit: Missing decimal point added
Edit2: ... and digit transposition corrected!

 

[EFLImpudence]

I'm not sure that I have seen a lamp/bulb described as G5.3 (they all seem to be GU5.3).

There are lots - Google it.
https://www.amazon.co.uk/Replacemen...TF8&qid=1480868204&sr=8-2&keywords=g5.3+bulbs

 

[JohnW2]

There are lots - Google it.

Fair enough - all I said was that I was not sure that I had seen any - and it remains quite possible that I hadn't!

Whatever, do you feel that you/we are any closer to understanding what differences (if any) there are between those described and G5.3 and those described as GU5.3, and to what extent they are interchangeable?? ... or do you perhaps feel that manufacturers using one of the designations are actually 'incorrect'?

Kind Regards, John

 

[stillp]

Do X, Y or Z appear in the list of defined second letters?

No.

if what I read previously is correct (that "U" indicates provision for mechanical restraint), it would not necessarily follow that a G5.3 could not be used in a GU35 holder (merely that the retaining clip/whatever would then be redundant.

Did you mean to type GU5.3?
Whether it would follow that a G5.3 lamp could not be used in a GU5.3 holder would, if what you read previously is correct, depend on just how that mechanical restraint was achieved.

 

[stillp]

do you feel that you/we are any closer to understanding what differences (if any) there are between those described and G5.3 and those described as GU5.3, and to what extent they are interchangeable?? ... or do you perhaps feel that manufacturers using one of the designations are actually 'incorrect'?

I can't find a G5.3 in the standard. There is a G5.3-4.8, which has two flat contact pins 4.8 mm wide. There is a drawing for GU5.3, but I can't see an explanation for the 'U'.

 

[EFLImpudence]

Fair enough - all I said was that I was not sure that I had seen any - and it remains quite possible that I hadn't!

Well, yes, but it does imply you thought there was none.

Whatever, do you feel that you/we are any closer to understanding what differences (if any) there are between those described and G5.3 and those described as GU5.3, and to what extent they are interchangeable?? ...

I am still under the impression that "G" do not have a base - i.e. just glass, capless.

As for interchangeability, I don't know what is achieved by preventing it if the voltage and wattage is the same.
Some with different voltage are interchangeable, aren't they?

or do you perhaps feel that manufacturers using one of the designations are actually 'incorrect'?

Definitely.

 

[JohnW2]

No.

If U, X, Y and Z do not appear in the "list of defined second letters", what letters do appear in that list??

Did you mean to type GU5.3?

Of course I did. Typo has been corrected.

Whether it would follow that a G5.3 lamp could not be used in a GU5.3 holder would, if what you read previously is correct, depend on just how that mechanical restraint was achieved.

Exactly - but, as I said, the other way around, IF a G5.3 lamp is deemed not to require mechanical restrainf (i.e. has no 'provision for mechanical restraint'), then presumably there is no reason why it could not be used in a GU5.3 holder (assuming it 'fits', which I assume it probably does) - it would probably merely mean that the holder's 'clip'/whatever would not be required, and would not be used?

Kind Regards, John

 

[JohnW2]

I am still under the impression that "G" do not have a base - i.e. just glass, capless.

That seems a bit different from the meaning of "G" in the Standard which stillp has told us about, doesn't it?

Kind Regards, John

 

[333rocky333]

Whatever, do you feel that you/we are any closer to understanding

I do
G4 etc are the capsule type lamps
GU4 etc are the M11 and MR16 type lamps, with the sguarer type base

G4 holder has no clip restraint, likely accepts either lamp type.
GU4 holder has some form of clip attached, designed to lock in GU4 lamps,would maybe also take a G4 lamp subject to size of lamp base fitting between clips, or possibly fitting and making the clip redundant.

Main point of GU in my opinion, to support the heavier GU type lamps from pin withdrawel and possible arcing

As with the "low voltage" and "transformer" sagas , I suspect a lot of the G and GU lamps and holders are wrongly described

 

[333rocky333]

Exactly - but, as I said, the other way around, IF a G5.3 lamp is deemed not to require mechanical restrainf (i.e. has no 'provision for mechanical restraint'), then presumably there is no reason why it could not be used in a GU5.3 holder (assuming it 'fits', which I assume it probably does) - it would probably merely mean that the holder's 'clip'/whatever would not be required, and would not be used?

Kind Regards, John

True, but I now believe, most fittings for a GU 5.3 lamp are designed for a GU5.3 MR 16 lamp, so a G5.3 type capsule lamp, although as you say fits, it would likely look crap.

Some open track fittings DO have the clips to support the MR16 type lamp base so id say they are true GU holders, fitted to support and hold secure the lamp.
whereas downlighters with circlips, the holders tend to have no clips, so appear to be made to take GU5.3 MR16 lamps but most actually have G5.3 holders (no clips)